The cycle's first race for a competitive House contest began in earnest Thursday, when Democratic state Rep. Steve Santarsiero filed paperwork to run in southeastern Pennsylvania's 8th District. Rep. Michael G. Fitzpatrick, R-Pa., has indicated he will not seek another term thanks to self-imposed term limits. On paper, the district is competitive: President Barack Obama narrowly lost it in 2012, while Fitzpatrick won re-election there by double-digit margins in the past two cycles. “It’s time we make Washington accountable to our citizens," Santarsiero, an attorney and former high school teacher, said in a statement. "I will make it a priority to focus on keeping the middle class families of the 8th District secure while helping to grow our economy, create jobs and bring real reform to Washington.”

At least one other candidate is considering a bid. Chemist Shaughnessy Naughton, who came within a couple points of the Democratic nomination in 2014, confirmed she might run a second time for the seat.

"Friends and neighbors are encouraging me to run again, so I'm thinking seriously about it," Naughton said in an emailed response to a CQ Roll Call inquiry.

Several Republicans named outgoing Lt. Gov. Jim Cawley as one of their top prospects for the race. But two Pennsylvania GOP operatives noted to CQ Roll Call he's considering other career options, including the private sector or a bid for state treasurer.

Republicans also named Robert Loughery, chairman of the Bucks County Commissioners, as another potential candidate, along with state Rep. Scott Petri. Neither Republican returned an email request for comment. Finally, local GOP operatives named one more candidate they'd like to see run: Fitzpatrick.

"There is a very concerted and unified effort to get Mike to run again," said a Pennsylvania Republican operative who was granted anonymity to speak candidly. "There is also no evidence that it is having an impact."

Fitzpatrick has said he will leave after this term, his fourth in Congress.

The 8th District includes the terrain on the northeastern side of Philadelphia, including Bucks County and a smaller part of Montgomery County. The city's pricey media market makes the district more expensive to run a campaign. Both nominees will have to raise millions to run viable operations in 2016.